One of the problems faced by an HIV/AIDS vaccine is the ability to protect against the diversity of isolates present in patient populations. The sequences that are most conserved are found in internal structural proteins. These conserved sequences contain epitopes that can be presented on major histocompatibility antigens to raise cell-mediate immunity, in addition to the humoral immunity that is often elicited by HIV/AIDS vaccines. DNA vaccination can elicit both humoral and cellular immune responses and can confer protection against several pathogens. However, DNA vaccines expressing only the HIV-1 envelope (Env) protein have been relatively ineffective at generating high titer, long-lasting, neutralizing antibodies in a variety of animal models. In order to elicit efficient immune responses to HIV-1 proteins, we propose to design and test a DNA vaccine expressing an HIV-1 virus like particle (VLP). This vaccine has been designed to elicit both humoral and cell-mediated immune responses to the major structural proteins of HIV, the Gag and Env gene products. The VLP has safety mutations designed into vaccine in order to meet U.S. government guidelines for vaccination into humans. DNA plasmids expressing these HIV-1 VLPs will be constructed and tested for efficient expression in vitro. Then, these plasmids will be inoculated into rodent model systems to test for immunogenicity to HIV-1 Gag and Env proteins. After successful completion of these studies, a second set of DNA expressing codon-optimized VLP constructs will be constructed. In addition, an ubiquitin-Nef fusion gene will be added to the genome of each of these codon-optimized DNA VLP vaccines and will be tested for elicitation of enhanced immunogenicity to HIV-1 gene products.